Zinc metabolism in non-insulin dependent diabetes mellitus

Low plasma zinc concentrations and increased zinc excretion have been reported in patients with non-insulin dependent diabetes mellitus (NIDDM). This study was designed to compare zinc metabolism in ten NIDDM patients with ten healthy controls, using stable isotopes of zinc. Zinc absorption from a standard breakfast labelled extrinsically with 3 mg 67Zn was measured using a fecal monitoring technique and thermal ionization quadrupole mass spectrometry. One hour after the test meal each volunteer was given 0.5 mg 70Zn (as citrate) intravenously and blood samples taken at intervals for up to 6 days. Isotopic enrichment was measured and the data entered into a simple kinetic model to estimate the size and rate of turnover of exchangeable pools of zinc. Urinary zinc excretion was higher in the male diabetics than controls (p < 0.05), but not in females. Since the efficiency of absorption and endogenous losses of zinc were very variable between individuals, and there was only a limited amount of data, it was not possible to draw conclusion about the effect of NIDDM on zinc absorption and excretion. However, the fact that there were no differences in exchangeable zinc pool sizes suggests that zinc metabolism is not altered in NIDDM.